The demand for low purity oxygen is increasing in applications such as glassmaking, steelmaking and energy production. Low purity oxygen is generally produced in large quantities by the cryogenic rectification of feed air.
Some users of low purity oxygen, for example integrated steel mills, often require some high purity oxygen in addition to low purity gaseous oxygen. While it has long been possible to produce some high purity oxygen along with low purity oxygen, conventional systems cannot effectively produce significant quantities of high purity oxygen along with low purity oxygen without a significant redesign of the column system.
Accordingly it is an object of this invention to provide a cryogenic rectification system which can more effectively produce both low purity oxygen and high purity oxygen with high recovery.